Rotary cathode x-ray tube equipment

Abstract

The rotary cathode X-ray tube equipment of the present invention is constructed so as to permit radiation of X-ray from all directions with respect to the whole circumference of a subject, and is used for x-ray CT. The equipment of the invention is constructed to prevent an X-ray radiation window 40 of a low strength from being influenced by atmospheric deformations of a vacuum vessel 1 or by machining and assembling errors, for example by using a joint portion disposed between the X-ray radiation window and an inner ring and having both a surface perpendicular to a rotational axis of a rotary member and a cylindrical surface parallel to the rotational axis, a face seal formed on the surface of the joint portion perpendicular to the rotational axis, and an axial seal formed on the cylindrical surface of the joint portion parallel to the rotational axis.

What is claimed is: 
     
       1. A rotary cathode X-ray tube equipment comprising: a ring-shaped hollow vacuum vessel;   a ring-shaped anode target fixed within said vacuum vessel;   a ring-shaped rotary member rotatably disposed in an opposed relation to said anode target within said vacuum vessel;   at least one cathode portion attached to said rotary member on the side opposed to said anode target;   an X-ray radiation window for passing X-rays generated at the anode target through the window, said X-ray radiation window being mounted to an inner ring of said vacuum vessel;   a rotary driving mechanism for rotationally driving said rotary member, said rotary driving mechanism comprising a rotor;   a magnetic levitation mechanism having a magnet for magnetic levitation which is fixed to said vacuum vessel; and   an object to be attracted which is fixed to said rotary member wherein said object to be attracted is fixed in position between said rotary member and said rotor of said rotary driving mechanism and integral with a portion of said rotor for reinforcing said rotary member.   
     
     
       2. A rotary cathode X-ray tube equipment according to claim 1, wherein said object to be attracted includes an inclined surface facing said magnet. 
     
     
       3. A rotary cathode X-ray tube equipment according to claim 2, wherein a non-contact type displacement meter for detecting a position of said rotary member measures a displacement of an inclined face of said object to be attracted for detecting the displacements of each of rotary axis direction and radius direction of said rotary member by one displacement meter. 
     
     
       4. A rotary cathode X-ray tube equipment according to claim 2, further comprising at least one touch-down bearing for supporting said inclined surface of said object to be attracted. 
     
     
       5. A rotary cathode X-ray tube equipment according to claim 1, wherein, said magnet for magnetic levitation comprises a yoke portion and only said yoke portion is arranged in said vacuum vessel. 
     
     
       6. A rotary cathode X-ray tube equipment according to claim 1, wherein a plurality of upper and lower magnets for magnetic levitation are provided so that the number of upper attractable magnets is larger than lower attractable magnets. 
     
     
       7. A rotary cathode X-ray tube equipment according to claim 1, wherein a plurality of upper and lower magnets for magnetic levitation are provided so that the upper attractable magnets are larger in size than the lower attractable magnets.